Abstract
Weed control remains a major challenge for economically viable grain sorghum production in the southeastern United States due to crop sensitivity to weed competition during early growth stages. Field experiments were conducted in 2012 and 2013 to determine the effects of grain sorghum row spacing, population density, and herbicide programs on Palmer amaranth control, crop growth, and grain yield. Treatments included row spacings of 19, 38, and 76 cm; grain sorghum population densities of 99,000, 198,000, 297,000, and 396,000 plants ha −1 ; and three herbicide programs: (1) a nontreated control, (2) S -metolachlor at 1,410 g ai ha −1 plus atrazine at 1,820 g ha −1 PRE, and (3) S -metolachlor at 1,070 g ha −1 plus atrazine at 1,380 g ha −1 PRE followed by 2,4 D at 330 g ha −1 POST. Palmer amaranth control benefited from the addition of a POST herbicide and from crop density ≥297,000 plants ha −1 . Under weedy conditions, Palmer amaranth density was not affected by narrower row spacing or increased crop density, whereas its dry biomass was reduced by 33% with 19 and 38 compared to 76 cm rows, and by 43% with ≥297,000 vs 99,000 plants ha −1 . Row spacing had no effect on light interception by the crop canopy. However, crop density influenced canopy closure with maximum light interception occurring one and a half weeks earlier for density ≥297,000 plants ha −1 . Yield increased by 18% for 19 vs 38 and 76 cm rows, whereas grain crop density had no effect. Overall, these results indicate that the combination of row spacing≤30 cm and crop density ≥297,000 plants ha −1 provided at least 97% Palmer amaranth control in the absence of POST application and reduced its biomass by 32% in nontreated plots compared to 76 cm row spacing and crop density≤198,000 plants ha −1 .
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Claims 12
Claim · model-written summary
Adding a POST herbicide improved Palmer amaranth control.
- Taxon
- grain sorghum
Sorghum bicolort0 - Treatment
- addition of a POST herbicidee0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth controle0
- Direction
- benefitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Palmer amaranth control benefited from the addition of a POST herbicide”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Crop density of at least 297,000 plants ha−1 improved Palmer amaranth control.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- crop density ≥297,000 plants ha −1e0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth controle0
- Direction
- benefitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Palmer amaranth control benefited from the addition of a POST herbicide and from crop density ≥297,000 plants ha −1”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Narrower rows did not affect Palmer amaranth density under weedy conditions.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- narrower row spacinge0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth densitye0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under weedy conditions, Palmer amaranth density was not affected by narrower row spacing”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Higher crop density did not affect Palmer amaranth density under weedy conditions.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- increased crop densitye0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth densitye0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Palmer amaranth density was not affected by narrower row spacing or increased crop density”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Rows of 19 and 38 cm reduced Palmer amaranth dry biomass by 33% versus 76 cm rows.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- 19 and 38e0
- Interactor
- Palmer amarantht0weed
- Outcome
- dry biomasse0
- Direction
- reducede0
- Value
- 33%e0
- Comparator
- 76 cm rowse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“its dry biomass was reduced by 33% with 19 and 38 compared to 76 cm rows”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
At least 297,000 plants ha−1 reduced Palmer amaranth dry biomass by 43% relative to 99,000.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- ≥297,000e0
- Interactor
- Palmer amarantht0weed
- Outcome
- dry biomasse1
- Direction
- reducede1
- Value
- 43%e0
- Comparator
- 99,000 plants ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by 43% with ≥297,000 vs 99,000 plants ha −1”
t0“Grain Sorghum and Palmer Amaranth”
e1“its dry biomass was reduced by 33% with 19 and 38 compared to 76 cm rows”
Claim · model-written summary
Row spacing did not affect crop canopy light interception.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- Row spacinge0
- Outcome
- light interception by the crop canopye0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Row spacing had no effect on light interception by the crop canopy”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
At least 297,000 plants ha−1 brought maximum light interception one and a half weeks earlier.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- density ≥297,000 plants ha −1e0
- Outcome
- maximum light interceptione0
- Direction
- earliere0
- Value
- one and a half weekse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“crop density influenced canopy closure with maximum light interception occurring one and a half weeks earlier for density ≥297,000 plants ha −1”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Nineteen-centimeter rows increased sorghum yield by 18% relative to 38 and 76 cm rows.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- 19e0
- Outcome
- Yielde0
- Direction
- increasede0
- Value
- 18%e0
- Comparator
- 38 and 76 cm rowse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yield increased by 18% for 19 vs 38 and 76 cm rows”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
Grain sorghum crop density had no effect on yield.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- grain crop densitye0
- Outcome
- Yielde1
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain crop density had no effect”
t0“Grain Sorghum and Palmer Amaranth”
e1“Yield increased by 18% for 19 vs 38 and 76 cm rows”
Claim · model-written summary
Combining rows at most 30 cm with crop density at least 297,000 plants ha−1 provided at least 97% Palmer amaranth control without POST herbicide.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- row spacing≤30 cm and crop density ≥297,000 plants ha −1e0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth controle0
- Value
- at least 97%e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the combination of row spacing≤30 cm and crop density ≥297,000 plants ha −1 provided at least 97% Palmer amaranth control in the absence of POST application”
t0“Grain Sorghum and Palmer Amaranth”
Claim · model-written summary
That combination reduced Palmer amaranth biomass by 32% in untreated plots against wider, lower-density planting.
- Taxon
- grain sorghumSorghum bicolort0
- Treatment
- row spacing≤30 cm and crop density ≥297,000 plants ha −1e1
- Interactor
- Palmer amarantht0weed
- Outcome
- biomasse0
- Direction
- reducede0
- Value
- 32%e0
- Comparator
- 76 cm row spacing and crop density≤198,000 plants ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced its biomass by 32% in nontreated plots compared to 76 cm row spacing and crop density≤198,000 plants ha −1”
t0“Grain Sorghum and Palmer Amaranth”
e1“the combination of row spacing≤30 cm and crop density ≥297,000 plants ha −1 provided at least 97% Palmer amaranth control in the absence of POST application”
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See all 21 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.